RESUMEN
Many techniques have been developed to overcome the bioavailability problem of poorly soluble drugs. The nanonization is one of the techniques in that micronized particle is converted in nanoparticle. Several processes are applied for nanocrystal production, including precipitation, milling, high pressure homogenization and combination method. The nanocrystal formulation is administered via various routes like oral, intravenous, intramuscular, pulmonary, ocular and dermal but due to safety, patient compliance and ease of administration, oral drug delivery is preferred. There are two basic ways to prepare drug nanocrystals like “bottom-up” and “top-down” technologies. The present literature provides an overview of the achievement in improving the bioavailability of the poorly soluble drug by using different methods.